For the open or closed loop control of internal combustion engines in motor vehicles, many quantities are available which can be detected by means of a potentiometer. These quantities are particularly the respective positions of the following: throttle flap, air flow measuring flap, accelerator pedal, or, for example, the control rack in a diesel fuel-injection pump. Some of these application examples for potentiometer data pick-ups require a highly accurate adjustment. However, in the mass-produced motor vehicle, this is not always without problems because especially drifts resulting from the aging of components as well as inaccuracies introduced by repair work must also be considered.
If the accuracy requirements regarding the adjustment of potentiometers are high, it is conventional practice to adjust the potentiometer sliders by means of fine adjusting screws. While this method permits a momentary calibration to be accomplished, its long-term accuracy is insufficient because of a number of circumstances.